1. Field of the Invention
The present invention relates to a circuit module, in particular a sensor module, which is preferably introducible as a tire sensor module into a vehicle tire, as well as to a vehicle tire having a circuit module of this kind.
2. Description of Related Art
Tire sensors are used, in particular, for measuring the internal tire pressure (tire pressure monitoring system, TPMS), as well as the temperature or the acceleration occurring inside of the tire. For this purpose, the sensor module typically includes a circuit substrate, respectively a substrate, at least one sensor component, and an antenna via which data are transmitted to a transceiver on the vehicle.
For the energy supply, besides electromagnetic wave irradiation, systems having an autonomous, battery- or galvanic cell-based energy supply are known, in particular. However, environmental protection requirements entail high disposal costs, as well as a substantial outlay for separation processes during disassembly. Tire sensor modules having batteries are typically mounted on the tire rim, since the galvanic cells used as batteries must be disposed of separately from the rubber tire material and since they do not tolerate the temperatures that occur inside of the tire during vulcanization. Furthermore, the service life is limited by the capacity of the battery which frequently is not replaceable; since the sensor module is limited in size, the batteries must also not be dimensioned to be too large.
The use of piezoelectric elements for supplying power or energy to autonomous modules is generally not without its problems, since the piezoelectric elements are typically fabricated from brittle ceramics and the flexural stress that occurs in response to deflections can, therefore, lead to destruction. Higher-complexity systems equipped with piezoelements often have larger space requirements which can lead to higher costs and, in some instances, to an unacceptable size when the module is integrated in a vehicle tire.